In recent years, governmental agencies involved in the regulation of foods and food additives have begun to reassess the potential risk to human health arising from the use of food additives and food machinery lubricants of petroleum origin. In February 1989, the United Kingdom Ministry of Agriculture, Fisheries and Food recommended a ban on virtually all direct food applications of mineral hydrocarbons, including white mineral oils. The United Kingdom decision was based in large part upon toxicological findings reported recently with white oils in rats by industry. Concern over the health safety of white oils indicates a need to examine alternative hydrocarbon materials such as synthetic polyalpha olefins as suitable non-toxic substitutes.
In the United States all food grade oils must meet the exacting requirements of the Food and Drug Administration (FDA). Lower viscosity grades, those up to 36.8 centistokes at 40.degree. C., are covered by U.S. National Formulary specifications, and the more viscous grades, above 38.1 centistokes at 40.degree. C., by the U.S. Pharmacopoeia. The latter grades closely correspond to the product designated as "liquid paraffin" by the British Pharmacopoeia (BP), although the BP limits viscosity to 64 centistokes, minimum, at 40.degree. C. The more viscous grade is also sometimes referred to as "medicinal liquid paraffin" by virtue of its use as a mild laxative. As can be appreciated, when employed for this purpose, the product must be of the highest quality and purity. A major use for food grade oils, also known as "food grade white oils" is in the lubrication of machines in which the lubricant may come in contact with foodstuffs. Other white oils, known to those skilled in the art as "technical white oils" do not require the same high level of refining necessary to meet pharmacopoeia requirements.
Petroleum-based white mineral oils are highly refined, water-white products made from lubricating oil distillates. These oils are complex mixtures of saturated hydrocarbons including straight chain, branched, ring structures and molecules containing all three configurations. White mineral oils typically have carbon numbers in the C.sub.15 through C.sub.30 range. The relative number of saturated ring structures and straight or branched chain structures will determine whether the oil is characterized as naphthenic or paraffinic in nature. White mineral oils are obtained from the intensive treatment of a petroleum fraction with sulfuric acid or oleum, by hydrogenation, or by a combination of sulfuric acid treatment and hydrogenation. The petroleum fraction is obtained by atmospheric and vacuum distillation to isolate the desired boiling range and viscosity and then solvent treated and dewaxed to remove polar compounds, aromatics and waxes.
Two FDA regulations govern the use of white oil and mineral oils as food grade lubricants:
21 CFR 172.878 Specifications for qualification as a white mineral oil; and
21 CFR 178.3620 Specifications for white oils for applications involving incidental food contact.
21 CFR 172.878 includes specifications for ultraviolet (UV) light absorbance, readily carbonizable substances and sulfur compounds. 21 CFR 172.878 specifies 15 uses or intended uses for white mineral oils. The FDA-approved uses are: 1) as a release agent binder or lubricant in or on capsules and tablets containing flavoring, spices and the like intended for addition to food; 2) as a release agent binder or lubricant in or on capsules and tablets for special dietary use; 3) as a float on fermentation fluids in the manufacture of vinegar and wine; 4) as a defoamer in food; 5) in bakery products, as a release agent and lubricant; 6) in dehydrated fruits and vegetables, as a release agent; 7) in egg whites, as a release agent; 8) on raw fruits and vegetables, as a protective coating; 9) in frozen meat, as a component of a hot- melt coating; 10) as a protective float on brine used in the curing of pickles; 11) in molding starch used in the manufacture of confectionary; 12) as a release agent, binder, and lubricant in the manufacture of yeast; 13) as an antidusting agent in sorbic acid for food use; 14) as a release agent and as a sealing and polishing agent in the manufacture of confectionary; and, 15) as a dust control agent for wheat, corn, soybean, barley, rice, rye, oats and sorghum. Where stated limits are given by the FDA for the above intended uses, never is the white oil percentage permitted to exceed 0.6%.
Findings from recent industry conducted toxicity studies in rats have raised some health concerns P. Watts, Mineral hydrocarbons in food--a ban?, BIBRA Bulletin, 28: 59-65,(1989)!. Repeated administration of conventional white oils in the diet (over 90 days) leads to the accumulation of oil droplets in the lymph nodes, liver, spleen and other target tissues in the animals. At high doses, this is accompanied by granuloma formation which is considered to be toxicologically important. Hematological and clinical chemistry abnormalities were also observed in these studies which are indicative of probable adverse health effects. While many other animal studies have not produced similar effects and there have been only rare indications of adverse effects in humans despite the many years in which mineral oils have been used in food and medicinal preparations (e.g., laxatives), the use of such petroleum-based products is expected to come under continued scrutiny, with further recommendation for banning anticipated.
There exists a need to consider alternatives to white mineral hydrocarbon lubricants for use in food and pharmaceutical applications. It is known within the field of engine lubrication that certain synthetic liquids exhibit properties that are superior, from a standpoint of lubrication, to those exhibited by white oils. Hydrogenated oligomers of 6-12 carbon atom alpha olefins, as described in U.S. Pat. Nos. 3,382,291, 3,149,178 and 3,725,498 represent such a class of synthetic liquids.
In addition to possessing desirable lubricant characteristics, hydrogenated polyalpha olefin materials may offer an advantage over conventional white oils in another manner. Because of their polymeric nature and high molecular weight, polyalpha olefin materials are expected to be poorly absorbed when ingested orally. The non-absorbability of hydrogenated polyalpha olefins diminishes the likelihood of accumulation in the tissues and therefore reduces the chance of adverse effects (e.g., granuloma formation) in the tissues, thus leading to a safer non-toxic product. The notion of `nonabsorable` polymeric food additives has been documented in the literature J. P. Brown and T. M. Parkinson, Nonabsorable food additives through polymeric design, Drug Metabolism Reviews, 16:389-422(1985)!and represents a recent approach towards developing safer food substances. There exists a need to apply this concept toward petroleum derived lubricants such as synthetic hydrogenated polyalpha olefins.
There remains a need for synthetic hydrocarbon materials such as hydrogenated polyalpha olefins which are not readily absorbed in mammals and which are suitable for direct use in foods and pharmaceuticals and which can serve as suitable safe alternatives to conventional white mineral hydrocarbons in such applications.